How Justin Theroux Wished 'Fierce' Jennifer Aniston a Happy Birthday

Jennifer Aniston's exes are coming out of the woodwork for her 50th birthday!

After ex-husband Brad Pitt was spotted attending her birthday party over the weekend, Justin Theroux took to his Instagram on Monday -- Jen's actual b-day -- to share his well wishes, too.

"Happy Birthday to this fierce Woman," he captioned a photo of Jen holding some horns over her head. "Fiercely loving. Fiercely kind. ....and fiercely funny. ❤️ you B."

Aniston and Theroux tied the knot in 2015, before they announced their split in 2018 after two and a half years in marriage. "We are two best friends who have decided to part ways as a couple, but look forward to continuing our cherished friendship," they said when they confirmed their separation.

Their joint statement added, "Above all, we are determined to maintain the deep respect and love that we have for one another."

In September 2018, Theroux opened up a little more about the split while speaking with the New York Times.

"The good news is that was probably the most -- I'm choosing my words really carefully -- it was kind of the most gentle separation, in that there was no animosity," he explained. "Neither one of us is dead, neither one of us is looking to throw hatchets at each other. It's more like, it's amicable. It's boring, but, you know, we respected each other enough that it was as painless as it could be."

"It was heartbreaking," he added, "only in the sense that the friendship would not be the same, as far as just the day to day. But the friendship is shifting and changing, you know, so that part is something that we're both very proud of."

Jen celebrated her birthday over the weekend with a bash attended by Pitt, as well as Kate Hudson, Gwyneth Paltrow, Katy Perry, Sandra Bullock, Reese Witherspoon, Lisa Kudrow, Courteney Cox, John Mayer, Barbra Streisand, David Arquette, Robert Downey Jr., Ellen DeGeneres and Diane Keaton.